1. Field of the Invention
The present invention relates to permanent magnetic material, predominantly containing cerium misch-metal (CeMM) and cobalt and to a process for the production of the same.
2. Description of the Prior Art
This type of material has already been variously described in the literature. For example, D. V. Ratnam and M. G. H. Wells, (AIP Conf. Proc. 18, American Institute of Physics, New York) have reported the properties of certain misch-metal/cobalt magnets. They disclosed individual magnets with energy products of up to 15 MGOe and coercive fields of up to 14 kOe. However, these magnets show demagnetizing curves of only moderately pronounced rectangular shape.
Cerium misch-metal is the term used for the light rare earths, separated from ores. For example, B. V. Kleber and B. Love (Technology of Scandium, Yttrium and the Rare Earth Metals, Pergamon Press, New York 1963, p. 10), report that Bastnaesite and Monazite, respectively, show the following percentage contents of rare earths:
______________________________________ Bastnaesite Monazite ______________________________________ La 30 38 Ce 50 48.5 Pr 4 3.6 Nd 14 8.8 Sm 1 0.5 ______________________________________
As can be seen, the composition of cerium misch-metal is not constant but fluctuates according to the starting ore. For the most important constituents, cerium, lanthanum, neodymium and praseodymium, the contents generally fluctuate at least between 45 and 55, 20 and 40, 5 and 14, and 0 and 5 atom-percent, respectively. Thus, it is certainly not surprising that it is difficult to produce magnets containing cerium misch-metal such as samarium magnets with a cerium misch-metal additive, which have satisfactory properties with reproducible values from magnet to magnet.